Interannual variability refers to variations in climate or weather patterns that occur on a time scale of one year or less. These fluctuations can be caused by natural factors such as changes in ocean currents, solar radiation levels, and atmospheric circulation patterns, as well as human-induced factors like greenhouse gas emissions and land use changes. Interannual variability is an important aspect of climate research because it helps scientists understand the short-term impacts of climate change on ecosystems, agriculture, and human societies.